The present invention generally relates to gelling formulations and their use in preparing gelled products. More particularly, this invention is directed to formulations including delayed-action acidulants that provide improved open time attributes to the formulation whereby the formulation can be deposited in a pre-gelled state and subsequently gelled within a selected mold or container in order to prepare gelled products in a manner more suitable for use within mechanized filling operations which can take advantage of a delay between the time that the pre-gelled formulation is prepared and the time that the formulation begins to gel to a significant degree. Formulations making use of such delayed-action acidulants are also capable of preparing final products having desired gel strengths with optimum usage of pectin.
Within the pectin gel food industry, it is well known that pectin gel formulations should include a source of solids, typically sugars or the like, a gel forming agent, usually pectin, and agents for controlling the pH of the formulation, typically a food grade acid in combination with a buffering agent, all within a aqueous system, which often can be characterized as a syrup. It is generally understood that the sugar solids and the acid combine to modify the pectin such that the modified pectin causes the aqueous system to gel, it being generally accepted that sugar is involved in the gelling mechanism by hydrogen bonding with the pectin, that water which is the medium in which the other ingredients are dissolved or suspended is also involved in the gelling mechanism, and that the gelling mechanism is triggered by the pH of the formulation.
There are general interrelationships among these ingredients in the formulations; for example, when a formulation includes a relatively high solids content, gel setting will occur with relatively less pectin or with relatively less acid, and formulations containing relatively high pectin levels will gel set when such formulations contain relatively low quantities of solids or acid.
Materials known as pectins are methoxylated esters of polyglacturonic acid and are hydrophilic colloids that hydrate slowly, although they dissolve in aqueous systems when mixed. Pectins are generally classified according to the number of methoxyl groups sybstituted on the ester backbone, this classification often being referred to as the degree of methylation (DM). A degree of methylation less than about 50 DM is generally understood in the art to refer to a "low methoxyl" pectin having an average of fewer than about 7 methoxyl groups on the pectin ester molecule, while a pectin classified as being at or greater than about 50 DM is understood in the art as being a "high methoxyl" pectin having an average of 7 or more methoxyl groups per pectin ester molecule. The "high methoxyl" pectins are usually further classified as either "slow set" pectins having an average of about 7 to 10 methoxyl groups, and "rapid set" pectins having an average of more than about 10 methoxyl groups on each molecule of pectin. While the present invention has been found to be suitable for either high or low methoxyl pectins, stronger gels typically will be formed when the so-called high methoxyl pectins are used. Actually, low methoxyl pectins gel by a mechanism different from that of high methoxyl pectin formulations and require the presence of a divalent ion, as described in Ross U.S. Pat. No. 3,185,576.
It is generally recognized that a slow set pectin formulation will have an optimum gelation pH of between about 2.8 and 3.2, while that for a rapid set formulation is between about 3.4 and 3.8, meaning that hydrogen ion concentration needed for effecting gel setting of a rapid set formulation is lower than that needed for a slow set formulation. When the solids content of a formulation is relatively high, such as when it is desired to substantially reduce or completely elminate a drying operation after the formulation has been deposited into a mold or filled into a container, the solids content must be approximately the same as that needed for the finished product. However, when these higher solids formulations are used, they tend to set prematurely to the extent that, for example, for a slow set formulation, the formulation will set at a pH as high as 3.6, meaning that the formulation will not achieve its optimum pH between about 2.9 and 3.2, whereat maximum gel strength is typically attained. Substantially the same problem is observed with regard to rapid set formulations, except that the pH for premature setting is on the order of about 4.0.
When the pectin food product is in the nature of a confection, the targeted final solids content is usually between about 80 and 85 weight percent, based upon the total aqueous system, being roughly equivalent to a moisture content of between about 15 and 20 weight percent. A pectin gel formulation that is in the nature of a table spread will have a lower solids content and a correspondingly higher moisture content inasmuch as it is necessary that such products be spreadable, a typical solids content for a finished product being in the 68 to 72 weight percent range, the moisture level accordingly being between about 28 and 32 weight percent of the total final formulation.
Advantages can be gained for pectin gel food formulations when they are prepared to contain relatively low quantities of pectin, both from the point of view of economy and from the point of view of reducing potential syneresis problems which are aggravated by the presence of pectin, especially when dealing with the higher moisture content products such as table spreads. Also, relatively high levels of pectin will tend to bring about the problem of premature gel formation whereby a product will not achieve its optimum gel strength, which is particularly important for confection gel products.
It is also generally advantageous to prepare formulations that exhibit "open time", which is understood to refer to the amount of time that elapses between completion of the formulation and when the phenomena of irreversible gel setting is observed. The need to obtain some degree of open time is particularly critical in the pectin confectionery jellie industry, in which formulation batches are prepared, and small quantities thereof are each deposited into starch or rubber molds, the open time permitting deposition of a pre-gelled formulation which gels within the molds. While table spreads are generally deposited into larger containers, it can often be desired to prepare formulations exhibiting an open time adequate to avoid pre-gelling within the container filling machinery whereby the setting will occur within the filled container only, which can bring with it the advantageous effect of achieving a relatively high gel strength with a relatively low amount of pectin to reduce syneresis tendencies.
In the past, open times of limited duration have been achieved by one or more avenues, some of which are discussed in Gallager, L. C. "Pectin Confectionery Jellies", Sunkist Growers, Ontario, California. They includes maintaining the formulation at temperatures as elevated as possible which has some effect in prolonging open time, although not to an extent sufficient to prevent premature gelation in most cases. Another approach is to deposit the formulation at a solids content lower than that desired for the final product and thereafter dry the deposited product in order to raise the solids content and thus enhance gelation, although such a drying procedure is expensive and can damage the final product. Another avenue is to adjust the active acidity or hydrogen ion concentration of the batch with a combination of a food grade acid, such as citric acid or malic acid, and a buffer, such as sodium citrate or sodium acetate. Typically, only part of the food grade acid will be initially added to the batch, while the remainder thereof will be added to the batch just before transferring it to the depositor apparatus in order to drop the pH within the setting range. Even with this last approach, premature gelling will occur unless deposition takes place within just a few minutes. If gelation progresses to a significant extent within the depositor, a weakly gelled final product will be prepared, it will be difficult to obtain a uniform count within a commercial, mechanized operation, and the formed confection jellie pieces will tend to be mishapened.
By the present invention, it has been discovered that the problem of providing adequate open time to substantially eliminate premature setting, the advantage of being able to utilize relatively low amounts of pectin, and the feature of being able to provide finished products having good gel strengths are all attained by replacing some or all of the food grade acid within pectin gelling formulations with a delayed-action or time-release acidulant having a hydrolysis rate such that the hydrogen ion concentration within the total system remains above that at which significant gelling will proceed, such hydrogen ion concentration increasing to gelation levels after a preselected open time has elapsed. Delayed-action acidulants can include anhydrides, esters, lactones, combinations thereof, and combinations thereof with rapidly hydrolyzing food grade acids, provided the overall formulation is an edible one.
It is therefore a general object of the present invention to provide improved pectin gel formulations, methods, and products.
Another object of this invention is an improved method for extending the open time of pectin gel formulations, and products produced thereby.
Another object of this invention is to provide pectin gel formulations which efficiently use the particular pectin therin by permitting gelation to take place at a pH level that is optimum for bringing about gelation within the formulation.
Another object of the present invention is an improved method and products produced thereby, wherein products of desired gel strengths are maintained with formulations having a relatively low level of pectin.
Another object of this invention is an improved method of preparing pectin confectionery jellies while avoiding pre-gelling problems, and gelled products produced thereby.
Another object of the present invention is to provide an improved method, formulation and product produced thereby for in-situ preparation of gelled products within molds or containers.
Another object of this invention is an improved method and formulation utilizing relatively high solids levels in order to substantially lessen or eliminate the need to reduce the moisture content of, or dry, the formulation after deposition into a mold or a container.
Another object of this invention is to provide an improved pectin gel product that resists syneresis, especially when stored in contact with a low moisture product such as peanut butter.
These and other objects of this invention will be apparent from the following further detailed description thereof.
Delayed-action or time-release formulations prepared according to this invention are aqueous, sugar-containing systems that include pectin and an acidulant that works with the sugar to cause the pectin to gel the formulation after a predetermined open time during which gelling does not take place. The acidulant has a relatively slow rate of hydrolysis such that, during the open time, the hydrogen ion concentration within the formulation will be kept below levels that initiate significant gelation.
More particularly, sugar within the formulation can be provided by one or more of sucrose from cane or beet sugar, usually as a mixture with other poly-saccharide or mono-saccharide sweeteners such as corn syrup, sorbitol, xylitol, mannitol, or the like, from natural fruit pulps, extracts, or juices, all within an aqueous environment, which sugar sources provide a major portion of the solids content of the formulation adequate to prepare a final product have a desired moisture content. When a pectin confectionery jellie is being prepared, the typical final product solids content will be between about 76 and 85 weight percent, based upon the total weight of the product, although the solids content can vary according to the texture desired in the final product. A table spread would typically desirably have a lower solids content so that it remains spreadable after it is gelled, typical solids content being between about 65 and 72 weight percent, based upon the total weight of the table spread. In all cases, the solids content can vary somewhat depending upon the mouth feel, spreadability, and physical appearance desired. Generally speaking, formulations according to this invention should have a moisture level or solids content such that the solids content of the finally prepared gelled product is at or above 60 weight percent and below about 90 weight percent, based upon the total weight of the finally prepared product.
Usually, commercially prepared gel formulations contain fruit sources that are not adequate to provide pectin at levels high enough to promote adequate gelling. Accordingly, most formulations will have a supply of pectin added thereto. Most formulations would add a pectin of the high methoxy type, having a degree of methylation equal to or greater than about 45 DM, meaning that an average of about 7 or more of the 14 available acid groups thereof are methoxylated. While low methoxyl pectins can be included in the present formulations, the high methoxyl pectins are preferred. Of the high methoxyl pectins, it is further preferred to utilize "slow set" pectins having an average of about 7 to 10 methoxyl groups per pectin molecule, primarily because high methoxyl pectins of the "slow set" variety are more economical than those of the "rapid set" type having an average of more than about 10 methoxyl groups per pectin molecule.
Total pectin levels within the formulation, whether provided as a separate additive or whether provided from fruit sources within the formulation, need not be as high as those of commercial formulations not in accordance with this invention. Pectin levels in confectionery jellie formulations can be as low as about one weight percent, based upon the weight of the sugar formulation, which is usually roughly also about one weight percent of the total solids within the formulation and within the final product. In standard formulations, the amount of pectin can be as high as three weight percent, which is also a practical, economical upper limit for formulations according to this invention. When preparing formulations for table spreads, the amount of pectin desired will usually be lower than these pectin confectionery jellie formulation levels, typically between about 0.5 and about 1.5 weight percent, although these percentages can vary depending upon the formulation requirements.
The delayed-action or time-release acidulant is one exhibiting a hydrolysis rate such that the total formulation will be provided with hydrogen ions sufficient to initiate gelling after the desired open time has passed. Inasmuch as they are incorporated within food formulations they should, of course, also be edible in the levels at which they are used. Certain delayed-action acidulants, although when they are used alone might not provide the desired hydrolysis rate, can be combined with other, faster hydrolyzing acidulants in order to achieve the desired open time for the total formulation. By the same token, certain delayed-action acidulants according to the invention can exhibit hydrolysis rates that are too fast for achieving a desired open time, and these can be combined with slower-hydrolyzing acidulants as desired.
Delayed-action acidulants include anhydrides and esters, including internal esters such as lactones. The acidulant will be released to its acid form upon hydrolysis of an anhydride or an ester linkage when exposed to water. Examples are the anhydride of any edible acid, such as acetic anhydride, heptanoic anhydride, succinic anhydride, and glutaric anhydride; esters which are combinations of any edible acid and any edible alcohol, for example ethyl acetate, triacetin (glycerol triacetate), and other esters of glycerin, sugars, sorbitol, mannitol, or any of the other edible polyhydroxyl compounds; and lactones such as gluconodelta-lactone, glucuronolactone, propiolactone, butyrolactone, and isovalerolactone.
Preferred for use as the delayed-action acidulant is glucono-delta-lactone. A discussion of the properties of this lactone can be found in "Food Acidulants", Chemicals Division of Pfizer, Inc., Technical Information Bulletin, 1977.
The quantity of delayed-action acidulant to be used in formulations according to this invention will vary widely depending upon the particular acidulent used, the most important variable in this regard being the strength of the acid formed when the acidulant is hydrolyzed. For example, for the preferred delayed-action acidulant, the amount thereof can generally be said to range between about one and about five weight percent, based upon the weight of the sugar solution, which is roughly the same percentage based upon the weight of the solids within the formulation or the final product. Delayed-action acidulants which are stronger acids will have correspondingly lower weight percent ranges, while those that hydrolyze into weaker acids will be incorporated into formulations according to this invention at correspondingly higher weight percent ranges.
Other ingredients can be incorporated into formulations according to this invention, particularly those ingredients that are incorporated in standard gel formulations. Included are food grade acids to bring about an initial lowering of the pH to one that is particularly desirable for the formulation prior to addition of the delayed-action acidulant. Typical of such initial pH values are between about 3.9 and 5.5, depending upon the optimum gelling pH of the pectin within the formulation. Suitable food grade acids include malic acid and citric acid. Usually such food grade acids will be used in combination with a buffer in order to closely control the pH and, when desired, permit enhanced tartness of the formulation by allowing the incorporation of additional food grade acid without significantly further lowering the pH to undesired intial, pre-gelation levels. For example, up to about one weight percent of a buffer such as sodium citrate could be added, as could about one weight percent of a food-grade acid such as malic adid. Quantities of other ingredients will typically be relatively minor and will be generally on the order of the amounts that they are used in traditional formulations. Miscellaneous other typical ingredients include flavoring compounds, coloring agents, and the like.
When proceeding with the method according to this invention, an important aspect thereof is the incorporation of a delayed-action or time-release acidulant within a pectin gel formulation having an initial pH significantly higher than that of the optimum gelation pH of the pectin contained within the formulation. By this method, it is possible to achieve a significant open time to permit deposition into molds or containers and thereafter have the hydrogen ion concentration within the deposited formulation increase to achieve such optimum pH level of the pectin, with the result that relatively less pectin is needed in order to achieve a desired high gel strength.
More particularly, the method includes preparing a pectin aqueous formulation including a sugar-containing syrup and a pectin. Depending upon the particular formulation, it is then typically necessary to lower the pH of the formulation in order to provide it with an initial pH that is significantly higher than the optimum gelling pH for the particular pectin incorporated into the formulation. Generally, these various ingredients are simply blended together, cold tap water or the like being added as necessary, accompanied by agitation in order to provide a relatively homogeneous blend for the purpose of preparing a generally consistent final product. The blend is then boiled or cooked at a temperature in excess of 100.degree. C. (212.degree. F.), usually between about 222.degree. and 235.degree. F., the temperature at ambient pressure being controlled as desired in order to achieve a formulation have a pre-selected solids or moisture content, the cooking generally preparing a colloidal solution of pectin.
After cooking has been completed, the delayed-action acidulant is added and blended into the cooked formulation or colloidal solution formulation, which results in the step of providing a predetermined open time during which hydrolysis of the delayed-action acidulant within the formulation will proceed slowly enough in order to delay gelling or setting of the formulation until after the preselected open time has elapsed.
The length of the open time is almost exclusively a matter of choice. Usually, in order to facilitate deposition within commercial filling or depositing machinery, an open time in excess of five minutes, usually ten minutes or longer, such as thirty to sixty minutes, will be desired. Open times of in excess of hundreds of hours can be provided, should this be desired, although in most commercial operations, this would add a processing time feature that would be economically undesirable. Sometimes, an especially long open time can be advantageous when it is desired to continue to develop the set or the tartness of a product while in storage. Typical desired open times will be between 6 and 20 minutes.
Next, the formulation to which the delayed-action acidulant had been added will be filled into an appropriate container, such as a starch mold, a rubber mold, a glass jar, a sealable can, or a pouch. While therewithin, an in-situ gelling or setting step will take place in order to provide a final product having a predetermined gel strength. After the jellies are removed from their molds, they typically are "sanded" with granular sugar to provide a non-sticky product.
When coloring ingredients or flavoring agents are to be incorporated into the formulation, it is generally preferred that they be added after the cooking step so as to minimize flash off of flavor essences and deterioration of colors.
The initial pH of the formulation will be between about 4 and about 5.5. After in-situ hydrolysis and acidulation, the pH will be lowered to the optimum gelation pH for the particular pectin used. For example, a typical optimum gelation pH for a slow set, high methoxyl pectin will be between about 2.9 and about 3.2 or 3.3, while that for a rapid set, high methoxyl pectin will be between about 3.2 or 3.3 and about 3.6 or 3.7. Optimum gelation pH levels will also vary with the "grade" of the pectin, the values given herein generally being applicable for a 150 grade pectin.
Usually during such hydrolysis, a relatively low quantity of water within the formulation will be used up, which is of assistance in reducing the amount of water that is found in the final product or that has to be dried out of the deposited or filled product. For example, the amount of water used by 2.5 weight percent of glucono-delta-lactone in an 82 weight percent solids batch will increase the solids content thereof between about 0.05 and 0.1 weight percent. This is another aspect of the invention which can be useful in preparing formulations of predetermined solids content while reducing the amount of drying needed to form a final product having such solids level.
Products according to this invention are products that have been set from pectin gel formulations. The products include a gel network or matrix of sugar-type solids, the gel including pectin, acidulants, and other conventional ingredients such as flavorings, colorings, tartness enhancers, buffers, and the like. The gel will have a moisture level between about 28 and 35 weight percent, based upon the total weight of the formulation, when the product is of the table spread type, such as a jam, a jelly, a conserve, or a marmalade. When the products are pectin confectionery jellies, the moisture content will be somewhat lower, usually between about 15 and 24 weight percent, based upon the total weight of the product.
Table spread products prepared according to this invention are characterized by particularly effective utilization of pectin within the formulation. Poor pectin utilization can result in a soft, runny gel, or syneresis may be evident by the presence of fluid apart from the gel structure, which is most noticeable when the product has been disturbed, such as when it is spooned or spread on bread. These types of problems are particularly evident in products not according to this invention in which premature gelling has begun before the product is filled into its container, resulting in a disturbance of the gel structure. Syneresis of table spread formulations tends to become an increasing problem for the portions of formulation batches that are filled from the "bottom" of the batch, while those filled from a freshly prepared batch tend to exhibit fewer syneresis problems.
Products according to this invention, since they have been substantially completely gelled only in-situ, the gel structure, once formed, is not subsequently disturbed until it is consumed. In formulations not according to this invention, extra pectin is typically included within such products in order to increase gelling within the container so as to mask gel disturbance and attempt to reduce syneresis. Such additional pectin is not needed for formulations according to this invention.
Table spread products according to this invention can be prepared such that they are filled into containers with the product moisture level being relatively low while avoiding premature gelling prior to filling. Such relatively low moisture levels are particularly suitable for products that are prepackaged layers of the low moisture table spread with another spread of traditionally very low moisture content, such as peanut butter, with the result that the gelled table spread moisture level is much closer, or equal to, the moisture level of the other spread to thereby retard undesirable moisture transfer between the layers of the different spreads.
Pectin confectionery gel products according to this invention can be in either cast or slab form. The amount of solids in cast jellie products is usually between about 72 and 78 weight percent, although a higher solids content can be desirable to reduce or eliminate drying, and in a preferred embodiment of this invention, the formed and cast jellie product will have the solids content of a particularly desirable finished product, typically between about 80 and 85 weight percent. Although such higher solids content cast jellies require more fluidity to conform to the shape of the mold and prevent stringing, and require greater open time because of slower depositing times, these problems are generally substantially eliminated by products in accordance with this invention. Slab jellies of conventional formulations may show some gelation before the batch is leveled off, and this problem of lost gelling power is traditionally compensated for by adding pectin at levels higher than otherwise necessary, which compensation adjustment is not necessary in products of this invention.
When the product prepared according to this invention is to have a high tartness level, such as that characteristic of a citric acid fruit, the product can include additional amounts of food grade acids. The amount of tartness achieved is a function of the equivalent weight and the amount of the acid used, such acids being weak organic acids, for example citric acid, malic acid, tartaric acid, fumaric acid, acidic acid, succinic acid, lactic acid, and adipic acid. When a particularly high tartness level is needed which would lower the pH to below the desired initial pH level, the pH of the total formulation can be maintained by a suitable buffer, such as an alkali metal salt of any of the just-listed organic acids. Also, sugars within the system can impart a slight degree of buffering activity to the formulation.
Fruit gel products should have a relatively high titratable acidity, usually between about 8 to 15 meq/100 g, while products having spice or mint flavors or the like would typically have no organic acid added thereto. Within limits of food grade use, small quantities of mineral acids can be used to lower pH without achieving any significant titratable acidity. Titratable acidity can be arrived at by dissolving a sample of about 10 grams in warm water with agitation, after which it is then titrated to a phenothaelin endpoint with 0.1 N sodium hydroxide. The titratable acidity is expressed in meq/100 g of sample, which is equivalent to ten times the volume of sodium hydroxide titrated (ml) divided by the weight of the sample (grams).
Confectionery jellie products prepared according to this invention make use of the basic requirement that the hydrolysis of the delayed-action acidulant proceed slow enough to allow enough open time to fill receptacles, molds, or slabs, but fast enough to lower the pH to a suitable place to get a firm enough piece for handling in the desired time. This can be referred to as the handling pH, which does not have to be as low as the optimum gelation pH for the particular pectin used, which optimum pH can be reached at a later time during the process or while the final product is in its container. The hydrolysis should be such that the half life of the reaction is 2 minutes to 2 hours under the conditions of preparation, a preferable half life range being on the order of between 3 to 15 minutes.
The smaller the batch of a formulation and the faster the rate of fill, the less open time will be required. For instance, a typical table spread batch will be more advantageously prepared with a longer open time than that for a pectin confectionery jellie formulation being deposited into small starch or rubber molds.
Open time can conveniently be measured by means of a GT-4 gelation timer (Techne Corporation) which instrument has a plunger or disc that oscillates up and down at ten strokes per minute and is recorded on a digital readout counter, the machine generally being insensitive to viscosity changes. When this plunger is submerged in a sample of a just-prepared formulation, it will continue to oscillate until cross-linkage or gelation occurs, at which point it shuts off and thereby records the time to gelation. "Open times" provided herein were measured by such an instrument.
It is possible to determine gel strengths for table spread products by the IFT "Sag" method ("Pectin Standardization", Food Technology, Vol. XIII, No. 9, pages 496-500, 1959). The gel strength is expressed in pounds of sugar gelled by one pound of pectin in order to give a gelled product "sag" of 23.5 percent under the standard conditions of the IFT test.
In measuring the gel strength of pectin confectionery jellie products, the following procedure can be used, and was the one used in arriving at the gel strength values reported herein. Muffin cups, 11/8 inch deep and having a rim diameter of 23/4 inches were filled to the top with the particular sample, after which they were sealed with aluminum foil to prevent water evaporation and skin development. They were then allowed to set over night to develop a full gel strength, after which the samples were placed on a top loading balance and tared to zero. A 5/16 inch diameter rod was suspended in a guide tube vertically over the sample, the rod fitting loosely in the tube to allow free fall. The rod was rapidly depressed at an even rate until the gel was ruptured, and a reading in grams on the scale was recorded. Ten readings were taken on each sample and averaged. It was determined that, with such a test, a difference in the averaged readings of about 50 grams would be a significant difference at a 95% confidence level. A value of about 400 grams was determined to be a good average gel strength for a pectin confectionery jellie, with about 250 to 300 grams being a minimum acceptable value.